Histomorphometric Evaluation of Extraction Sockets and Deficient Alveolar Ridges Treated with Allograft and Barrier Membrane: A Pilot Study

The aim of the study was to determine the fate of demineralized freeze-dried bone allograft (DFDBA) used in conjunction with a barrier membrane in the management of extraction sockets and deficient alveolar ridges, and to compare the amount of bone formed with that found in untreated sites. Ten biopsies were obtained from 8 grafted patients. Five biopsies were harvested from untreated sites during routine implant placement and analyzed for comparison. In the socket management procedure, DFDBA was packed tightly into the socket and covered with an expanded polytetrafluoroethylene (e-PTFE) membrane. Primary closure was achieved in all cases. In the ridge regeneration procedure, cortical columns were placed in the ridge projecting outward approximately 3 mm to create and maintain space for DFDBA particles packed between them; the columns were then covered by an e-PTFE membrane. Healing time ranged from 8 to 23 months. At the time of implant placement, bone cores (7 mm X 2 mm) were harvested, fixed in 10% formalin solution, and prepared for histologic examination. At the light microscopic level, no inflammation or fibrous encapsulation was observed. New bone formation on and around DFDBA particles was widespread. Histomorphometric analysis of the grafted specimens and untreated sites was carried out using the trabecular bone volume (TBV) index. The TBV in the maxillary test specimens was 55.03%, as compared to 57.33% of control cores. Unaltered DFDBA made up 8.7% of the test specimens. In the mandibular biopsies, the TBV was 56.6%, while for the controls it was 40.9%. The volume of DFDBA still present was 2.45%. The results tended to indicate that treatment with DFDBA in conjunction with cell occlusive membranes will result in new bone formation, predominantly by the process of conduction, which appears to be similar in amount and nature to that found in cores harvested from healed nonfunctional edentulous areas. Keywords: deficient ridges, demineralized freeze-dried bone allograft, extraction sockets, guided bone regeneration, histomorphometry, osteoconduction